Commercial ceramic and glassware is often decorated by applying a pattern in colored ink on the surface of the substrate with screen printing, offset printing, or any other direct application technique. The glass is then baked at high temperatures to bond the design or indicia to the glass surface. This process, sometimes referred to as applied ceramic labeling (ACL), exhibits certain drawbacks. Often, the ink compositions contain heavy metals and volatile organic solvents (VOC's). Both VOC's and heavy metals are undesirable from the environmental point of view. Second, ACL requires high temperature ovens for the baking step, which results in considerable energy usage and an increased potential for worker injury due to the high temperatures at which the process operates. Moreover, the high temperature ovens are expensive, cumbersome pieces of equipment which require considerable floor space in factories.
On the other hand, use of ultraviolet (UV) radiation curable organic pigmented inks for the decoration of glass and ceramic ware is very desirable. Organic inks generally can be cured by exposure to radiation, such as ultraviolet radiation, thus obviating the need for high temperature baking. In addition, UV curable organic inks can be formulated to contain little or no VOC's or other nonaqueous solvents. One problem with organic inks, however, is that it is difficult to duplicate the adhesion found with ACL decorated glass. For example, ACL provides decorated glass containers where the indicia or decoration are essentially adhered permanently, and it is quite difficult, if not impossible, to remove the decoration from the glass surface. The same is not true of glass substrates decorated with organic inks. In general, to find organic inks which will adequately adhere to glass to a degree sufficient to pass various tests necessary for use in commerce is quite difficult. There is a need to develop better ink compositions and methods for decorating glass and ceramicware, to work toward the goal of providing UV curable, organic-based-ink decorated glass which equals ACL decorated glass in durability and commercial application.